Abstract: Disclosed is a method of making a polymer containing more than 50 to about 95 mole percent, preferably 65 to 80 mole percent, of units derived from maleic anhydride and the balance units derived from at least one 1-alkene. The method comprises mixing the maleic anhydride and 1-alkenes selected in the presence of a thermally decomposable initiator and, optionally, in the presence of a solvent at a temperature ranging between 145.degree. C. to 200.degree. C., in such a manner that throughout the process, the ratio of maleic anhydride to 1-alkenes is more than 50:50 to about 95:5, most preferably between 65:35 to 80:20, to form a reaction mixture and thereafter maintaining the reaction mixture at from 145.degree. C. to 200.degree. C. until a polymer containing more than 50 mole percent of maleic anhydride is obtained.